Wheel with suspension system

ABSTRACT

A wheel with a suspension system being connectable to a vehicle, like a wheel chair. The wheel includes a hub and a rim rotatable about the axle of the hub. Between the hub and the rim, a number of support members is located. The support members are adapted to retain the distance when stressed up to a threshold value and recoverly alter the distanced when stressed over this threshold value. Exemplary support members are spring elements, damping strokes by compression if the support member is compressed or elongated. The spring elements may be preloaded.

RELATED APPLICATIONS

This application is a Divisional of U.S. patent appl. Ser. No.14/354,607, filed on Apr. 28, 2014, entitled: “Wheel With SuspensionSystem And Centralizing Unit With Suspension System”, which is aNational Phase of PCT Patent Application No. PCT/IB2012/001994 havingInternational filing date of Oct. 8, 2012, which claims the benefit ofpriority under §119(e) of U.S. Provisional Patent Application No.61/552,505, filed on Oct. 28, 2011.

PCT Patent Application No. PCT/IB2012/001994 is also aContinuation-In-Part (CIP) of PCT Patent Application No.PCT/IB2012/000530 having International filing date of Mar. 20, 2012,which claims the benefit of priority under §119(e) of U.S. ProvisionalPatent Application No. 61/552,505 filed on Oct. 28, 2011 and of U.S.Provisional Patent Application No. 61/485,086 filed on May 11, 2011.

The contents of all the above applications are incorporated by referenceas if fully set forth herein in their entireties.

FIELD AND BACKGROUND OF THE INVENTION

The present invention refers to a wheel with a suspension system. Suchwheels can particularly be used in self-propelled vehicles, like wheelchairs and bicycles. Furthermore, these wheels can also be used forsuspension of any rotatable mass including wheels of motorized orotherwise powered vehicles.

Furthermore, the present invention refers to a centralizing unitcomprising a suspension system, whereby this centralizing unit may,according to the invention, be part of a wheel.

Rotating masses tend to accommodate vibrations and shocks due tointernal and/or external forces and impacts from surfaces in contact.One example is the vibratory motion of a wheel when it travels adistance on a non-purely smooth surface. Motorized and other vehiclescommonly include cumbersome suspension systems in order to protect theirchassis or other affiliated parts from early failure as well as to avoidunpleasant conditions to passengers.

Suspension systems, mostly including springs and spring elements, arecommonly connected to static parts of the machine or vehicle, on oneend, and in direct contact with the axle or other elements that providea stable axis of rotation to the rotating mass or rotator. For example,a wheel that travels over a rough surface will transfer axial, verticaland other forces (e.g., impacts and/or vibratory) to the axle, whichwill be partially absorbed and diminished using suspension means thatcan be located between the axel and the chassis. Several attempts areknown for implementing suspension mechanisms inside the wheels.

In recent years there is a growing trend towards more efficientself-propelled vehicles where the invested human power is transferred tomovement of the vehicle with minimal energy loss. Modern wheelchairs andbicycles incorporate lightweight structural parts, wheels structureswith improved strength-weight ratio, tires designed for minimizedresistance to rolling, etc. There is also a preference of most riders tofeel a rigid or responsive ride, rather than a soft one, especially whendriving over substantially smooth surfaces and/or when riding upwardinclines, and also when accelerating, decelerating or maneuvering. Whensuspension is implemented the manufacturers usually make some acceptedtradeoffs between the physiological and improved comfort needs with thedynamic preferences of the users.

From GB 2 188 596, it is known to provide a wheel of a wheel chair withresilient spokes. These spokes are located non-radial so that the spokescan be flexed due to an impact. This wheel has the possible drawbackthat due to the high stress of the spokes, the spokes may break.

Another wheel having an implemented suspension mechanism inside thewheel is known from DE 10 2005 032 537. This car wheel has radiallocated spokes that are comprising an hydraulic damper. The possibledrawback of the use of such dampers is that the damping characteristicsby compressing the damper differ from the damping characteristics byelongating the damper. Since the wheel has a number of regularly locateddampers, a damper being located opposite to the damper being compressed,has to be elongated. Due to the different damping characteristics, therotation of the wheel becomes uneven. Furthermore, the dampers describedin DE 10 2005 032 537 cannot be preloaded.

SUMMARY OF THE INVENTION

Therefore, it is one object of the invention to provide a wheel,particularly a wheel for self-propelled vehicle such as a wheel chair ora bicycle, having a smooth and even damping system.

This and other objects are solved by a wheel according to claim 1. Andby a centralizing unit according to claim 26.

The present disclosure can be related or implemented in any rotatablemass including wheels having a hub in concentric relation with a rim,when in nominal state.

A wheel according to the invention is connected or connectable to avehicle, particularly to a self-propelled vehicle, a wheel chair or thelike, or to other vehicles like cars, motorbikes etc. The wheel has ahub comprising an axle or being connectable to an axle. This hub maycomprise a bearing, whereby particularly an inner ring of the bearingcan be connected to the axle. Furthermore, the wheel comprises a rimbeing rotatable around the axle. The rim may particularly comprise awheel rim, a tire, a hub, a bearing outer ring etc. Between the hub andthe rim, at least one, particularly a plurality of support members, arelocated. The support members are normally providing a fixed distancebetween the station member and the rim. According to the invention, thesupport member is adapted to retain this distance when stressed up to athreshold value and to recoverably alter this distance when stressedover this threshold value. According to embodiments of the invention,this function of the support member is derived by a spring member, beingpart of the support member or building the support member. The springmember stores mechanical energy at compression, and in a preferredexemplary embodiment, the spring member is preloaded to a predeterminedthreshold value, thereby compresses only to compressive forces greaterthan the threshold value. In some embodiments, the spring memberincludes or is coupled or otherwise functionally linked to a damper,that is effectively operable (e. g., absorbs or dissipates kineticenergy) only during spring member change of size, or optionally onlyduring its compression. In some embodiments, the spring member is inboth ways compressed by the stroke, if the support member compresses andif it elongates. By compressing the spring member independent ofcompressing or elongating the support member, an identical dampeningcharacteristic is optionally given. Therefore, the present invention hasthe advantage that particularly a wheel having a number of supportmembers being located between the hub and the rim, can be smoothlydamped, preferably only at strokes or shocks in a magnitude above apredetermined threshold value. Within a preferred embodiment of theinvention, the supporting member comprises two longitudinal elementsbeing slidably connected to each other. The two longitudinal elementsare optionally comprising two cylinders, or a cylinder and a rod, onelocated inside the other. The spring element and/or damper can belocated in and/or between the two longitudinal elements so that arelative movement of the longitudinal elements to each other causes thespring element and/or damper to be compressed.

In some embodiments, both end portions of the spring element and/ordamper are connected to one of the two longitudinal elements, wherebyoptionally, both end portions of the spring element are connected to theinner longitudinal element. In this preferred embodiment, the springelement surrounds the outer longitudinal element. In another preferredembodiment the connection is the other way around so that both endportions of the spring element are connected to the outer longitudinalelement, whereby the spring element is preferably located inside theinner longitudinal element.

In some such optional embodiments, fixing elements are connected to theend portions of the spring element and the inner or the outerlongitudinal element. These tracked sliding elements are preferablypassing through longitudinal slits, which are preferably located in bothlongitudinal elements. The outer ends of these longitudinal slits beingdirected in the damping or moving direction of the damper are thestoppers of the damper. If the damper is preferably preloaded, bothtracked sliding elements are pressed against the outer ends of thelongitudinal slits due to the force of the damper caused by preloading.The tracked sliding elements are connecting the spring element to theinner or the outer longitudinal element and having preferably a pin-likeshape.

The spring element may include a spring, optionally a coil compressionspring or a piston spring, pneumatic or hydraulic. In case of a pistontype spring, the spring element may include damping function as well,for example if a piston member thereof is provided with at least oneminute opening allowing travel of flowable medium passing therethroughduring strokes, in a way that transforms kinetic energy to heat by fluidfriction. A damper may be provided as a separate member, optionallyhydraulic cylinder type (e.g., “dashpot”), liner or rotary, or amechanical damper operating on dry friction between solid components, anhysteresis type damper (e.g., metal or polymeric compressionstructures).

Furthermore, the plurality of supporting members is optionally connectedto the hub in a non-radial manner. Therefore, a compression force causedby an impact to a lower located supporting member of a wheel will not betransferred directly to the axle of the wheel, but at least partlyguided surround the axle of the wheel causing an elongation of a supportmember being located in an upper position. Such a non-radialconfiguration has several advantages, including increased stroke lengthof the support member and inner spring element and/or damper andincrease in overall stability and/or strength of the entireconstruction. Furthermore, when the hub shifts away from concentricitywith respect to the rim and the suspension is activated, the non-radialconfiguration of the interconnecting supporting members causes the hubalso to rotate about its axis with respect to the rim, so thatparticularly a piston type spring element and/or damper will avoidpotential “sticking” phenomena, for example if the altering force isorthogonal thereto at the stroke initiation.

Therefore, in embodiments, the hub comprises particularly radiallyarranged arms, whereby the supporting members are connected to the outerend portions of these arms.

Optionally, the supporting members are pivotably connected to the huband/or the rotatable member of the wheel.

In one embodiment, the supporting members are arranged symmetricallyaround the hub so that the distance of neighbored supporting members areequal.

In another embodiment, two supporting members are building a pair ofsupporting members, whereby it is preferred that a plurality of pairs ofsupporting members is arranged, whereby the pairs are symmetricallylocated around the hub. In this embodiment, it is preferred that the endportion of the arms of the hub has two protrusions, whereby a supportingmember is connected to each one of the protrusions. Two supportingmembers being connected with end portions of different arms form a pairof supporting members. The two supporting members of this pair ofsupporting members are located symmetrically to a radial line betweenthe axle of the hub and the rim.

In some embodiments of the invention, the vehicle is a self-propelledvehicle, for example a wheelchair or a bicycle. In some embodiments, thewheel is a rear wheel in a wheelchair. In some other embodiments, thewheel includes a caster which is fixedly rotatable about at least twoaxes projecting from the vehicle. In some embodiments of the invention,the hub includes at least one of: an axle, a caster housing, and abearing inner ring. In some embodiments, the rim includes at least oneof: a tire, a wheel rim, a hub shell, a fork, and a bearing outer ring.

In some embodiments of the invention, the threshold value relates to aminimal shock magnitude absorbed by the wheel. Alternatively oradditionally, the threshold value relates to a minimal vibrationamplitude absorbed by the wheel. Alternatively or additionally, thethreshold value reciprocally relates to a maximal vibration amplitudeabsorbed by the wheel. Alternatively or additionally, the thresholdvalue reciprocally relates to a maximal vibration frequency absorbed bythe wheel.

Furthermore, in an aspect of some other embodiments, the inventionrefers to a centralizing unit optionally comprising a suspension system.The suspension system comprises at least one support member. Thissupport member has an outer longitudinal element and inner longitudinalelement as described above in view of a preferred embodiment of thewheel. Particularly, the outer longitudinal element includes a lumen andcomprises two slots, atop outer slot and a bottom outer slot.Additionally, the inner longitudinal element being slidable in the lumenof the out longitudinal element, comprises also two slots, a top innerslot and a bottom inner slot. A sliding pin is located in each of thetwo top slots and the two bottom slots. Between the two sliding pins, aspring element is located being connected to both pins. The slots aresized and arranged so that the central relative position between the twolongitudinal elements the top pin and the bottom pin are pushed by aspring to a maximal distance. At any non-central relative positionbetween the longitudinal elements, the pins are forced to approach eachother to a distance smaller than the maximal distance, therebycompressing the spring located between the two pins.

The spring element is preferably preloaded so that the nominal length issmaller than a non-stressed length of the spring.

In a preferred embodiment of the centralizing unit disclosure, thecentralizing unit comprises a central member connected at a firstportion thereof to a first support member and at an evenly displacedsecond portion thereof to a second support member. Preferably, a thirdsupport member is connected to the central member, whereby the number ofsupport members is evenly displaced. The support members are preferablyidentical. Loading a central member having two support members willcause one support member to elongate and the other support member tocompress, whereby both spring elements of the two support members arecompressed so that a cumulative compression force thereof resists theloading. The same principle that the spring elements are compressed evenif the support member is elongated, occurs if a larger number of supportmembers is particularly symmetrically located around a central member.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter, preferred embodiments of the invention are described,referring to the drawings.

FIGS. 1A-B schematically illustrate side views of a wheelchair and awheel anticipating different obstacles during motion, in accordance withembodiments of the present invention,

FIGS. 2A-C illustrate an exemplary wheel comprising a plurality of spoketype selective suspension members in accordance with a first preferredembodiment of the invention, invention,

FIGS. 4A-C are showing side views of the spring element used within thewheel shown in FIG. 3 in different damping situations, and

FIGS. 5A-C are showing diagrams of bilateral spring mechanisms.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The following preferred embodiments may be described in the context ofexemplary suspension mechanisms for wheelchairs, or other types ofself-propelled vehicles, for ease of description and understanding.However, the invention is not limited to the specifically describeddevices, and may be adapted to various applications without departingfrom the overall scope of the invention. For example, devices includingconcepts described herein may be used for suspension of any rotatablemass including wheels of motorized or otherwise powered vehicles.

Common suspension systems are built to absorb interruptions andobstacles which cause deceleration and/or undesired vibration to thevehicle and/or aid the wheel in following the terrain and avoiding lossof contact with it, or grip. In doing so, the suspension systems arebuilt to absorb and/or dissipate energy, including such that can betranslated to effective kinetic energy. Furthermore, the commonsuspension systems (which include, for example, parts like metalsprings, cushioning materials and elastomers) cause a feeling ofplushness, or softness, which may cause a sense of instability, whichare undesirable by many users.

In order to answer these and other considerations, the present inventionprovides or includes means for selective responsiveness (orirresponsiveness) according to types and/or magnitudes of absorbedinterferences or perturbations.

Referring now to the drawings, FIGS. 1A-B schematically illustrate sideviews of a wheelchair 10 and a rear wheel 11 anticipating differentobstacles during motion, in accordance with embodiments of the presentinvention. Besides combining two rear wheels such as wheel 11,wheelchair 10 further includes a seat 12 and a pair of casters 13. InFIG. 1A, wheelchair 10 moves along path 20 which includes a step or acurb descent 21 with height x, as well as a plurality of recesses 22,such as tile gaps or chamfers on paved surfaces. Height x may be about10 cm or more in case of a sidewalk curb, or 15 cm or more in case of astandard stairway step. Recesses 22, on the other hand, are of heightsof less than 3 cm, usually around 1 cm. In some embodiments, thesuspension system of the present invention includes means for selectivedifferentiation between drops from different heights, for example dropsfrom up to 1 cm, optionally up to 3 cm and those which are equal orhigher than 1 cm, optionally 3 cm, optionally 5 cm, or higher, or loweror intermediate. Also, a selective differentiation may be applicable fora range of drops or perturbations, such as over 3 cm and under 10 cm,for example.

Wheelchair 10 is shown in motion adjacent a forward-facing step 21 withits front end is tilted upwardly (commonly known as performing a“wheelie”), pivoting around rear wheel(s) 11—a common practice whenriding over steps, performed either by an attendant or by the wheelchairuser himself. The tilting angle α may be between 0 to 40°, andoptionally higher. Such tilting maneuver changes the impact angle of thewheelchair with the ground and should be considered when designing aneffective suspension mechanism. In some embodiments, the suspensionsystem of the present invention is configured for effective suspensionof falls at different impact angles, optionally in angles range of atleast −10° to 10°, optionally −30° to 30°, optionally −60° to 60°. Also,in some cases the drop can be taken in reverse, meaning that the rearwheels go first, while the front casters are still on the top platform,generating a mild “nose up” angle of generally less than 20°, butoptionally higher.

FIG. 1B shows a second demonstrative scenario in which wheel 11 (shownindependently for ease of demonstration only) travels along path 30 thatincludes a bump 31 of a significant height followed by a substantiallyshallow coarse road 32. In some embodiments, the suspension system ofthe present invention includes means for selectively differentiatingbetween bumps of different heights, and for example may allow suspensionof bumps of 0.5 cm or higher, optionally 1 cm or higher, optionally 3 cmor higher. Alternatively or additionally, such or other means may allowsuspension of bumps shorter in height than wheel radius, optionallyshorter than ¾ its radius, optionally shorter than ½ its radius.Alternatively or additionally, such or other means may differentiatebetween road types (such as between coarse roads like road 32) whichcause vehicle's and/or wheel's vibrations differentiated by accelerationimpact amplitude and/or frequency, optionally depending also onvehicle's velocity. In some such embodiments, the suspension selectivityis also based on a defined allowed load (e.g., combined weight ofwheelchair and user) or on a defined allowed range of loads, so thatonly if such a condition is met, the suspension system can correctlydifferentiate between such predetermined fall heights. For example, asuspension system according to the present disclosure can be provided intwo rear wheels of a wheelchair, and provided and preset such, that if acombined weight of the wheelchair and a wheelchair user is, for example,between 40 Kg to 120 Kg, or optionally between 50 Kg to 100 Kg, oroptionally between 60 Kg to 80 Kg, or optionally about 70 Kg, or higheror lower or an intermediate value, then the suspension system will notoperate at shocks originating from falls of 40 mm or less, optionally 20mm or less, optionally 10 mm or less, optionally 5 mm or less,optionally 2.5 mm or less, in height, or higher or lower or anintermediate value.

Reference is now made to FIGS. 2A-C which illustrate an exemplary wheel700 comprising a plurality of spokes type selective suspension members740 (or 760), with a first embodiment of the present invention. Wheel700 includes a rim 710 wearing a tire 720, a hub 730 and the pluralityof members 740 that are symmetrically and evenly distributed andconnecting between rim 710 and hub 730. In some embodiments, members 740support a fixed distance, under a compressive forces of less than athreshold magnitude, between hub 730 and contact regions (e.g., flanges715) at rim 710. Optionally, members 740 do not maintain or onlypartially support circularity of rim 710, and therefore the latter isoptionally provided strengthen with respect to previously shown rims. Insome embodiments, hub 730 includes a center rounded portion 736 having abore 738 passing therethrough and housing a bearing (not shown)mountable to a chassis (e.g., of a wheelchair) using an axle. Threeoutwardly radial extensions 734 originate from hub center 736; eachradial extension 734 ends with an angularly extended head 732; eachangularly extended head 732 includes two lateral sides; wherein eachlateral side is hingedly connected to an inward connection portion 742of a member 740. Member 740 includes an outward connection portion 746which is hingedly connected to rim 710 at flange 715. Each member 740includes a piston 741 slidably movable in a cylindrical housing 745.Both piston 741 and housing 745 includes linear slots (744 and 748,respectively) provided along and in parallel to their longitudinal axes,and each include a movable pin (743 and 747, respectively) that isslidably movable in a corresponding slot (pin 743 in slot 748 and pin747 in slot 744). A preloaded compression spring 750 is providedconnected in-between pin 743 and 747. Spring 750, when fully relaxed orcompressed under a predetermined threshold value (according topreloading), maintains pins 743 and 747 at a normally fixed distance.When piston 741 and housing 745 are subject to compression or extensionstresses that are over the predetermined threshold value, the pinsultimately move one towards the other thereby compressing spring 750. Adamping member (not shown) may also be provided and configured to act inparallel to contraction motions of spring 750. Member 760 is analternative design that can replace member 740, and while preservingsimilar qualities, it is based on gas spring 770 instead of coil spring750. Similarly, when member 760 elongates or shortens at stressesexceeding the threshold value, gas spring 770 will be forced tocompress. In some embodiments, gas spring 770 includes dampingcapabilities, as known in the art.

Within FIGS. 3 and 4A-C, a second preferred embodiment of a wheelconnectable to a vehicle, particularly to a wheel chair, is shown. Wheel10 comprises a rim 34 carrying a tire 36. The rim 34 is connected to ahub 38 by three supporting members 40. An axle 42 is shown provided inhub 38, being in this embodiment surrounded by bearing 44. The innerring of the bearing 44 is fixed to the axle 42 and the outer ring of thebearing 44 is fixed to a connecting member 46 having three arms 48. Thearms 48 are particularly arranged radially to the axle 42. The supportmembers 40 are connected to the outer end portions of the arms 48 sothat the support members 40 are not arranged in a radial manner in thewheel.

To damp a stroke or the like, the length of the support members 40 varydamping the stroke.

Within the drawings 4A-C, the support members 40 are shown in differentdamping situations.

In a regular, normal situation (i.e., hub 38 in concentric with rim 34),each of the support members 40 centralized and are not compressed orelongated, and a spring 50 provided therein is substantially preloaded(e.g., it is held compressed to a length being substantially smallerthan its non-stressed length).

The support members comprise two longitudinal elements 52 and 54,whereby the cylindrical element 54 surrounds the inner cylindricalelement 52. Therefore, it is possible to move the two longitudinalelements 52, 54, relative to each other in a longitudinal direction 56.Within the inner longitudinal element 52, the damper 50 is located. Thespring 50 comprises a piston 58, being located within a cylinder 60. Thecylinder 60 is, for example, filled with compressed gas or oil. Spring50 is preloaded since at nominal position, the pins 62 are distancedsuch that the spring is already compressed to the threshold value. Onlyabove the threshold it can be further compressed. The end portions ofthe spring 50, i.e. of the cylinder 60 and the rod 58, are eachconnected to a pin-like tracked sliding element 62. The pin-like trackedsliding elements are passing through slits 64 of the inner longitudinalelement 52 and slits 66 of the outer longitudinal element 54. Due to theslits 64 and 66, a movement of the two longitudinal elements 52, 54 inlongitudinal direction 56 is possible. Slits length provide boundariesto such relative motion, above which pins 62 are forced to move.

As shown in FIG. 4B, combined acting forces F and -F compress supportmember 40. The force actuates and compresses spring 50, due to the factthat rod 58 is pressed into the cylinder 60 compressing the air in thecylinder 60. Optionally and additionally, spring 50 acts as a damper sothat some of the kinetic energy invested by the force work is dissipatedand the stroke is absorbed. Additionally, the left tracked slidingelement 62 is moved within left slits 64, 66. The right tracked slidingelement 62 remains in place.

In some embodiments, when at least one support member in aself-suspended wheel or in a centralizing unit according to the presentinvention, there is at least a second support member being elongated,optionally at same extent, optionally to a different extent. In somesuch embodiments, springs and/or damper installed in both supportmembers shall compress during the first support member compression andthe second support member elongation, such that both springs and/ordampers contribute to the overall mechanical energy storage and/ordamping, respectively. Reference is now made to FIG. 4C, showing thatthe support member 40 is now elongated by a force F. According to theinvention, the spring 50 is compressed, i. e. the rod 58 is, forexample, compressing gas provided in the cylinder 60, even if thesupport member 40 is elongated. This is possible due to the fact that inthis case, the left tracked sliding element 62 is held in place comparedto the normal position (FIG. 4A), whereby the right tracked slidingelement 62 is moved to the left in FIG. 4C. This movement is possiblesince the right tracked sliding element 62 can be moved to the leftinside the slit 66 of the outer longitudinal element 54, whereby thismovement is caused by moving the inner longitudinal element 52 to theleft in FIG. 4C.

A centralizing unit according to the invention may comprise a centralmember 48 being connected to three support members 40, whereby thecentral member 38 does not necessarily have to be connected to a hub andthe support members 40 do not necessarily have to be connected to therim (see, for example, FIG. 3).

The principle mechanism background of a bilateral spring mechanism ishereinafter described in view of FIGS. 5A-5C.

Virtually, an infinite spring, such as a coil spring, that adheres tothe linear rule of elasticity, would demonstrate substantially the sameratio between elongation to required force as it would betweencompression to required force (often referred to as ‘k’, or springconstant).

Therefore, if such a spring is allowed to work both as a pulling springand as a compression spring, its behavior as depicted in the graph ofFIG. 5A.

In most suspension systems the spring is installed with some portion ofcompression preload, in order to prevent the spring to be free at anypoint, hence diminishing unwanted movement of the spring while not undercompression forces (see graph of FIG. 5B).

As a preloaded spring is inherently stressed in one direction (e.g.,compressed), if it is prone also to shift to the opposite direction(e.g., extend) then the preloading function will not be efficient.

Therefore, while compressing the system for a certain travel (e.g., 2cm) would require a certain amount of force, elongating the system bythe same travel would require less force.

The disclosures provided herein allow bilateral suspension orcentralizing unit and obviate the need for two such mechanisms (orsub-systems) to be installed in opposite directions, in order to for amirrored image of the graph shown in FIG. 58.

When a symmetrical preloaded springing system is implemented, bothcompression and elongation produce the same forces, in their respectivedirection, while allowing preloading function in both directions, asshown in FIG. 5C.

Such a “mirrored” springing system enables several benefits that areimpossible with one-directional springs, like a bi-directional thresholdand symmetrical suspension response using a single sprung element whileother applications that deals with cyclic or periodic perturbations mustuse two systems installed in opposite directions.

The principal of a bi-directional threshold can be described aspreventing motion in any direction, as long as force above a certainmagnitude, like F_(min), is not exerted on the system. In this setup,any force, in any direction, that is lower than F_(min), will not deriveany movement of the spring, and only forces higher than F_(min) willcause the spring to travel at k ratio, in either direction (without anyspecial push/pull connection).

1. A wheel with suspension system being connectable to a vehicle, thewheel comprising: a hub (38, 736) a rim (34, 710) and a suspensionsystem with at least one support member (40, 740) positioned betweensaid hub (38, 736) and said rim (34, 710) thereby providing a normallyfixed distance therebetween; wherein said support member (40, 740) isadapted to retain said distance when stressed up to a threshold valueand to recoverably alter said distance when stressed over said thresholdvalue, characterized in that said at least one support member (40, 740)comprising a spring element (50, 750), configured to compress from anominal length, if the support member (40, 740) compresses and if thesupport member (40, 740) elongates.
 2. A wheel according to claim 1,whereby the spring element (50,750) is preloaded in its nominal length.3. A wheel according to claim 1, characterized in that the supportmember (40, 740) comprises a damping element, whereby the dampingelement is preferably integrated into the spring element (50,750).
 4. Awheel according to claim 3, characterized in that the support member(40, 740) comprises two longitudinal elements (52, 54) being slidablyconnected to each other.
 5. A wheel according to claim 4, characterizedin that one of the longitudinal elements (52, 54) is at least partlylocated inside the other of the longitudinal elements (52, 54).
 6. Awheel according to claim 5, characterized in that both end portions ofthe spring element (50) are connected to at least one of the twolongitudinal elements (52, 54).
 7. A wheel according to claim 3,characterized in that the damping element (750) surrounds the outerlongitudinal element (745).
 8. A wheel according to claim 3,characterized in that the damping element (50) is located inside theinner longitudinal element (52).
 9. A wheel according to one of claim 3,characterized in that the damping element is a spring (750) and/or afluidic damper (50).
 10. A wheel according to one of claim 8,characterized in that the damper element (50) is connected, preferablyslidably coupled, to the inner and/or outer longitudinal element (52,54) by use of particularly pin-like tracked sliding elements (62).
 11. Awheel according to claim 10, characterized in that the tracked slidingelements (62) are passing through longitudinal slits (64, 66),particularly located in the inner and/or outer longitudinal element (52,54).
 12. A wheel according to one of claim 1, characterized in that thesupport members (40, 740) are connected to the hub (38, 736) in anon-radial manner to wheel center.
 13. A wheel according to claim 12,characterized in that the hub (38, 736) comprises particularly radiallyarranged arms (48, 734), whereby the support members (40, 740) areconnected to the outer end portions of the arms (48, 734).
 14. A wheelaccording to one of claim 1, characterized in that the support members(40, 740) are pivotally connected to the hub (38, 736) and/or the rim(34, 710).
 15. A wheel according to one of claim 13, characterized inthat each end portion of the arms (334) having particularly twoprotrusions, is connectable to supporting members (740).
 16. A wheelaccording to claim 15, characterized in that two supporting members(740) being connected with end portions of different arms (734) form apair of supporting members (740) being located symmetrically to a radialline between the axle (738) of the hub (736) and the rim (710).
 17. Awheel according to one of claim 1, wherein said vehicle is a selpropelled vehicle.
 18. A wheel according to one of claim 1, wherein saidvehicle is a wheelchair.
 19. A wheel according to one of claim 1,wherein said hub comprising at least one of: an axle, a caster housing,and a bearing inner ring.
 20. A wheel according to one of claim 1,wherein said rim comprising at least one of: a tire, a wheel rim, a hubshell, a fork, and a bearing outer ring.